One of the present inventors has conducted studies for some time in order to work out a muscle strength increasing method for easy, safe, and effective muscle development, and put together the accomplishments into a patent application having Japanese Patent Application No. 5-313949, which has been granted as Japanese Patent No. 2670421.
The muscle strength increasing method according to the subject patent, which involves the application of pressure, is a distinctive non-conventional one called a “Pressure Muscle Strength Increasing Method”. This muscle strength increasing method is based on the following theoretical concept.
Muscles are composed of slow-twitch muscle fibers and fast-twitch muscle fibers. Slow-twitch muscle fibers are limited in their potential for growth. Accordingly, it is necessary to recruit fast-twitch muscle fibers of the slow- and fast-twitch muscle fibers in order to develop muscles. Recruitment of fast-twitch muscle fibers causes lactic acid buildup in the muscles, which triggers secretion of growth hormone from the pituitary. The growth hormone has effects of, for example, promoting muscle growth and shedding body fat. This means that recruitment and exhaustion of fast-twitch muscle fibers results in development of fast-twitch muscle fibers and, in turn, the entire muscles.
Slow-twitch muscle fibers and fast-twitch muscle fibers are different from each other in terms of the following. Slow-twitch muscle fibers use oxygen for energy and are recruited for low-intensity activities. Fast-twitch muscle fibers provide for activities regardless of whether or not oxygen is present. They are recruited after the slow-twitch muscle fibers for highly intense activities. Therefore, it is necessary to cause the earlier recruited and activated slow-twitch muscle fibers to be exhausted soon in order to recruit fast-twitch muscle fibers.
Conventional muscle strength increasing methods use heavy exercises with, for example, a barbell to cause the slow-twitch muscle fibers to be exhausted first, and then to recruit the fast-twitch muscle fibers. This recruitment of fast-twitch muscle fibers requires a significant amount of exercises, is time-consuming, and tends to increase the burden on muscles and joints.
On the other hand, when a predetermined range of muscles near the top of a limb is compressed and pressurized to restrict the blood flow therethrough before muscle exercises, less oxygen is supplied to these muscles. The slow-twitch muscle fibers, which require oxygen for energy, are thus exhausted in a short period of time. Muscle exercises with blood-flow restriction by application of pressure will result in recruitment of the fast-twitch muscle fibers without needing a large amount of exercises.
In addition, restriction of the blood flow by application of pressure makes the lactic acid built up in the muscles less likely to be removed from the muscles. Thus, the muscle lactic acid level is more likely to rise and a much larger amount of growth hormone is secreted, as compared with the case where the blood flow is unrestricted.
Based on this theoretical concept, to restrict the muscle blood flow can provide significant development of the muscles.
The muscle strength increasing method according to the aforementioned patent is premised on the theoretical concept of the muscle strength increase by the restriction of blood flow. More specifically, a compression pressure for the blood flow restriction is applied to a range near the muscles that you want to develop and closer to the heart, i.e., a proximal region near those muscles. The compression pressure is controlled to put an appropriate stress attributed to the reduced blood flow on the muscles, thereby causing muscle fatigue. In this way, effective muscle development is achieved.
This muscle force increasing method has a significant feature in muscle development not necessarily requiring exercises because it involves developing muscles by putting a stress attributed to a reduced blood flow on the muscles. In addition, this muscle strength increasing method can compensate for a total amount of stress that is placed on the muscles by putting a stress attributed to a reduced blood flow on the muscles. When combined with some exercises, the method advantageously provides a less exercise-related stress than conventionally. This advantage brings about some effects: the possibility of incurring damages to the joints or muscles can be reduced and the period of training can be shortened, as a result of decrease in amount of muscle exercises.
The implementation of this muscle strength increasing method requires a muscle strength increasing device or apparatus that can restrict the blood flow through the muscles that you want to develop and can provide accurate control of the degree of blood flow restriction. In particular, the function that can provide accurate control of the degree of blood flow restriction in muscles is very important in order to enhance effects obtained using the pressure muscle strength increasing method and to improve the safety of the pressure muscle strength increasing method.
One of the present inventors has made studies for a muscle strength increasing device. In the course of these studies, he made an invention relating to a muscle strength increasing device as disclosed in Japanese Patent Application No. 8-248317. The muscle strength increasing device according to this invention comprises a tight fitting device, which is a bag-shaped belt, having a rubber-made tube provided therein. It is designed to compress muscles and thereby to apply a desired compression pressure to the muscles when a gas is introduced into a tube with the tight fitting device rest on and fastened around a predetermined range of muscles.
Such a muscle strength increasing device of the type that achieves compression using a gas has the advantage of allowing detailed control for the compression pressures by means of measuring a gas pressure. However, it still has a point that should be improved.
Such a muscle strength increasing device is said to be able to measure the compression force applied by the muscle strength increasing device to muscles by measuring the gas pressure within the aforementioned tube. The compression force applied to muscles, which is determined according to the measurement of the gas pressure, provides information that is used to predict the degree of blood flow restriction in muscles. In the aforementioned muscle strength increasing device, an appropriate degree of blood flow restriction is tried to be achieved by changing the gas pressure within the tube based on this prediction.
However, people have individual differences as well as other variations over time, such as gains and losses in body weight. This suggests that a constant compression force does not always result in the same degree of blood flow restriction, so that the above prediction is attended with difficulty.
Thus, the use of such a muscle strength increasing device requires an experienced person with a good knowledge about a pressure muscle strength increasing method who can teach how to use the muscle strength increasing device. In fact, the pressure muscle strength increasing method is carried out under the supervision of a person who is available for the coaching.
In addition, the pressure muscle strength increasing method has a potential use in preventing the decline of muscle strength and the decrease in bone density of an astronaut after having many months of zero gravity in a spaceship, which is a major concern in recent years. However, the distribution of blood through the body in a weightless state differs from that on earth. Accordingly, it is very difficult to predictively determine whether the resulting degree of blood flow restriction becomes appropriate even when a compression force is selected according to the experiences and knowledge about the pressure muscle strength increasing method accumulated on earth.
The present invention is for solving the aforementioned problem and an object thereof is to provide an art with which a muscle strength increasing apparatus can be achieved that is capable of providing accurate control of the degree of blood flow restriction.